Writing instrument



DeC- 20, 1966 M` D. CHAPMAN ETAL 3,292,592

WRITING INSTRUMENT n if? mm NRS a odmmdomd. 962.31818. o om ATTORNEY De@ 20 1966 M. D. CHAPMAN ETAL 3,292,592

WRITING INSTRUMENT 4 Sheets-Sheet 2 Filed Feb. 1. 1963 ATTORNMX Dec. 20, 1966 M. D. CHAPMAN ETAL 3,292,592

WRITING INSTRUMENT Filed Feb, 19. 1963 4 Sheets-Sheet 3 o-M` ATTORNEY Dec- 20, 1966 M. D. CHAPMAN ETAL 3,292,592

WRITING INSTRUMENT Filed Feb. 19. 1965 4 Sheets-Sheet 4 alla20o 1 23 23|229CL 232@ A xw FIG.I6

MERVIL O. CHAPMAN F|G.l8 BY JOHN J. ORRls United States Patent O 3,292,592 WRITING INSTRUMENT Mervil D. Chapman, 1403 Dorsch Road, South Euclid, Ohio 44121, and John J. Orris, 1504 Jaeger Drive, Lyndhurst, Ohio 44124 Filed Feb. 19, 1963, Ser. No. 259,570 31 Claims. (Cl. 1Z0-42.03)

The present invention relates to a writing instrument, such as a mechanical pen or pencil, and more particularly to a mechanical pen.

One of the objects of the present invention is to provide a writing instrument constructed to use a standard ballpoint pen rell cartridge, to advance or to retract a scribe element by a rotating movement, not only to so move the scribe element but also to couple or uncouple an exterior barrel and cap of the writing instrument by a rotating movement, to permit loading or unloading the scribe element therethrough at generally the mid-portion of the writing instrument, and/or to advance or to retract the scribe element by a positive, part-to-part drive instead of by a frictional drive.

A further object of the present invention is to provide for a writing instrument a plurality of different type couplings for joining the barrel and cap, different type helical drives for advancing or retracting the scribe element, different type connectors in a nut and screw-type scribe element advancing and retracting mechanism, different type drag elements, and/or different type scribe element gripping collets and/ or end stops.

A further object of the present invention is to provide a writing instrument characterized by its inexpensive manufacturing cost, ease of assembly of its component parts, structural simplicity, strong and sturdy nature, operating efciency, low operating cost, attractive exterior appearance, and/or multiplicity of functional advantages for some of its component parts.

These and other objects of the present invention will become more fully apparent by reference to the appended claims as the following detailed description proceeds in reference to the accompanying drawings wherein:

FIG. l is a side elevational view of a writing instrument showing a generic view to all forms of the writing instrument disclosed specifically herein as an automatic pen and shown with its scribe element in a partially advanced position short vof the writing position;

FIG. 2 is a longitudinal section of the writing instrument in FIG. 1 taken generally along the line 2-2 showing a first form of writing instrument but with the ball point tip shown respectively by dot-dash lines and solid lines in the advanced and retracted positions;

FIG. 3 is an enlargement of a portion of the longitudinal sectional view in FIG. 2;

FIG. 4 is an enlarged, transverse, cross sectional view taken generally along the line 4 4 in FIG. 2;

FIG. 5 is a longitudinal sectional view of a drive mechanism, shown in retracted position, and adapted to be substituted in FIG. 2 for the corresponding drive mechanism therein to make a second form of Writing instrument;

FIG. 6 is a longitudinal sectional view of a drive mechanism, shown in advanced position, and adapted to be substituted in FIG. 2 for the corresponding drive mechanism therein to make a third form of writing instrument;

pearance, as shown in FIG. 1.

ice

FIG. 7 is a longitudinal sectional view of a drive mechanism, shown in advanced position, and adapted to be substituted in FIG. 2 for the corresponding drive mechanism therein to make a fourth form of writing instrument;-

FIG. 8 is a longitudinal sectional view of a drive mechanism, shown in retracted position, and adapted to be substituted in FIG. 2 for the corresponding drive mechanism therein to make a fifth form of writing instrument;

FIG. 9 is a transverse, cross sectional View taken generally along the line 9-9 in FIG. 8;

FIGS. l0 and l1 are longitudinal, sectional views of second and third forms of coupling means adapted to be substituted for the corresponding coupling means in FIG.

FIGS. 12 and 13 are longitudinal sectional views of sixth and seventh forms of drag means, shown in retracted positions, and adapted to be substituted in the drive mechanism in FIG. 2 for the corresponding drag means found there;

FIGS. 14 and 15 are longitudinal sectional views respectively of sixth and lseventh forms of connectors adapted to be substituted for any of the other tive forms of connectors shown respectively in FIGS. 2 and 5, 6, 7, 8 `or 16;

FIG. 16 is a longitudinal sectional view of a sixth form of drive mechanism, shown in advanced position, and adapted to be substituted for the drive mechanism shown in FIG. 2;

FIG. 17 is a circumferential development of the cams and helical surfaces thereon in FIG. 16 shown in advanced position; and

FIG. 18 is a force diagram of the wedge actions at the coupling means and in the helical means, whether the helix is on a screw or on a barrel cam.

A plurality of diiferent forms of writing instruments are disclosed herein but each has the same exterior ap- These are shown, either partially 4or completely, as different forms of writing instrument 20 in FIGS. 2, 3 Vand 4; 40 in FIG. 5; 60 in FIG. 6; 80 in FIG. 7; 100 in FIGS. 8 and 9; 120 in FIG. 10; in FIG. 11; 160 in FIG. 12; 180 in FIG. 13; 200 in FIG. 14; 220 in FIG. 15; and 240 in FIGS. 16 and 17. All forms of the invention are generically shown in FIG. 1.

Reference numerals from 10 to 19 have been reserved for common parts found in all forms ofthe invention; and a set of twenty reference numerals, such as 20 to 39 or 40 to 59, has been reserved for each form of the invention with the corresponding numbers in all twenty reference number series being applied, whenever possible, to the parts having generally the same function, structure, or mode of operation.

Each form of the invention may serve as any suitable writing instrument, such as not only as the ball point pen specifically illustrated herein but also as the basic structure of a lead pencil or other suitable writing instrument.

Most of the features of all forms of the invention will be generically described at the same time by reference to the first and preferred form shown in FIGS. 2, 3, and 4. Thereafter, the difference between the different forms will be brought out in detail.

The outer shell of pen 20 in FIGS. 2, 3 and 4 includes oap member 10 comprising tubular sleeve 10a having sleeve bore 10d, tapered tip 10b pressed or screwed into one end of sleeve a, and pocket clip 10c secured to the periphery of sleeve 10a; barrel member 12 comprising tubular sleeve 12a having barrel bore 12d, and tapered tip 12b pressed or screwed into one end of sleeve 12a and having central bore 12f; and contiguous ends 10e and 12e respectively on cap member 10 and barrel member 12.

Pen may use any suitable form of scribe element 14, such as a ball point pen rell cartridge or pencil lead. Element 14 is here shown as a ba-ll point pen cartridge having ball point end 14a, opposite en-d 14b, and generally cylindrical periphery 14C connecting these opposite ends.

Coupling means 21 is movable between an uncoupled or detached position (not shown but with all parts carried by cap 10 completely detached from all parts carried by barrel 12) and a coupled position shown in FIG. 2 for detachably connecting by -a coupling movement contiguous ends 10e and 12e of cap and barrel mem-bers 10 and 12. Coupling means 21 includes male element 22 carried by cap -member 10 and ferrule or female element 23 secured by a force t in barrel bore 12d so that relative rotational -and/or telescoping movement applied to the outsides of members 10 and 12 causes corresponding movement of elements 22 and 23 for moving members 10 and 12 -between the uncoupled and coupled positions.

Suitable drive mechanism 24 in FIGS. 2 and 3 operatively connects cap and barrel members 10 and 12.

Mechanism 24 includes drive means 24a, responsive to relative rotational movements applied to members 10 and 12 in the coupled position shown in FIG. 2, for advancing (by an advancing movement in direction DA) or retracting (by a retracting movement in direction DR) bore 16 (located within writing instrument 20 and receiving scribe element 14) and scribe element 14 relative to barrel member 12 between an advanced or writing position PA shown in dot-dash lines in FIG. 2 with ball point end 14a projecting out through tip bore 12j and retracted position PR shown in solid lines in FIG. 2.

Mechanism 24 includes driver part 25 and driven part 27 respectively having coacting helical surfaces 25a and 27a respectively rotatable with cap member 10 and barrel member 12 for causing by relative rotation of members 10 `and 12 the aforedescribed advancing or retracting movement of said drive means 24a in direction DA or DR. The periphery of driver part 2S is rigidly carried by and is secured to cap member 10 by a press lit within bore 10d so that no relative axial or rotative movement can take place therebetween.

When cap and barrel members 10 and 12 are rotated, helical surfaces 25a and 27a cause movement of scribe element 14 in direction DA or DR. In the coupled position shown in FIG. 2, this is true because coupler 29 is operatively carried by barrel member 12, is rotatably connected to cap member 10 by component 31, and drives by a keyed connection driven part 27. Hence, coupler 29 is operatively connected to barrel member 12, driven part 27 and cap member 10 `for the following numbered reasons. First, since one end of coupler 29 is formed by male coupling e-lement 22, coupler 29 is rigidly carried by barrel member 12 in the aforedes-cribed coupled position so that neither relative vaxial nor relative rotative movement can occur therebetween. Second, coupler 29 and driven part 27 are connected by a keyed connection (comprising a telescopically connected, broached, hexagonal bore 29b and hexagonal tubing having hexagonal outer surface 27b but able to take the form of any other type suitable keyed or splined connection) permitting axial relative sliding movement of part 27 within coupler 29 in advancing direction DA and retracting direction DR but preventing relative rotative movement. Third, rotatable component 31 is secured by a press fit within cap bore 10d against relative axial and rotative movement. Coup-ler 29 has peripheral surface 29a and component 31 has bore surface 31a providing coacting relatively rotatable and telescoped surfaces fonning connection 32 to rotatably connect them together while preventing substantial axial relative movement between them.

Although component 31 and driver part 25 are shown as a one-piece part and male element 22 and coupler 29 are shown as a one-piece p-art in FIG. 2, it should be readily apparent that either or both one-piece parts may besp'lit into two parts, either directly connected together or through an intermediate part. For example, compare one-piece part 25, 31 in FIG. 2 with t-he comparable part in FIG. 16 comprising driver part 245 and component 251 rigidly joined together by barrel sleeve 10a.

As driven part 27 moves in either advancing direction DA or retracting direction DR relative to driver. part 25,`

it reaches at the end of its travel either advanced position PA oir retracted position PR. These positions PA and PR are respectively defined iby end stops 33a, 33h and 34a, 34b with stops 33a and 34a being located on part 25 and stops 33b and 34b being located on part 27. These end stops 33a, 33by and 34a, 34b are respectively engageable in advanced and retracted positions PA and PR to define different stop engaged positions LA and LR by the wedging action between these parts 25 and 27 caused by helical surfaces 25a and 27a. As will be brought out in more detail hereafter, helical surfaces 25a and 27a and coupling means 21 are constructed so that scribe element 14 can easily move between positions PA and VPR because these helical sur-.faces 25a and 27a are yalways unlockable from these locked positions LA and LR during relative rotation of cap and :barrel members 10 and 12 without uncoupling coupling imeans 21.

An inspection of the drawings will reveal that the description of the structural parts, directions, positions and mode of operation for FIGS. 2, 3, and 4 in the preceding paragraphs apply generically to the same named parts, directions, positions and modes of operation corre-` spondingly numbered in a dilerent twenty reference number series in FIGS. 5-17, inclusive.4

Now, the structural differences between the different forms of the invention will be brought out in the following paragraphs. Note that the similarly named component parts in each drive mechanism, etc. have generally the same function and mode of operation so are interchange able, either directly or with some modification. Hence, the scope of the present invention includes not only the com- 'bin-ations illustrated but other combinations where the last mentioned component parts are combined in different` manners.

Three different type coupling means 21, 121 and 141 are shown respectively in drawing FIGS. 2, 5-8 and 16;

10; and 11 as having male coupling elements 22, 122,l

and 142 carried by capmember 10 and female coupling elements 23, 123 and 143 canried by barrel member 12. In FIGS. 2, 5-8 vand 16, threads 22a and 23a on elements 22 and 23 have helical surfaces providing the coupling action by relatively rotating cap and barrel members 10 and 12. In FIG. 10, elements 122 and 123 have two rotatable and connectable bayonet surfaces 122a, 123e adapted to be locked together by a. sequential telescopic assembly and rotatable action of barrel 12 and cap 10 to the coupled position. securely locked in coupled position if elements 122 and 1.23 are either composed of resilient molded plastic materlal so yas to spring lock together or, if made of metal, have a resilient annular washer (not shown) located between elements 122 and 123 generally coplanar with the space betwen contiguous ends 10e and 12e. It should be apparent that both threads 22a, 23a and bayonet surfaces 122a, 123a have a rotatable wedge-type coupling surface coupling cap and barrel members 10 and 12 together in coupled position. In FIG. 11, coupling elements 142 and 143 respectively have two,- cylindrical, telescopi'cally and/ or rotatably connectable surfaces 142a and 143a having a snug, friction tit to provide a push-type and/or rotatabletype coupling action and a pull-type yand/or` rotatabletype uncoupling action.

Elements 122 and 123 will bei The driver parts and driven parts, and the helical surface on each, for causing advancing and retracting movement in directions DA and DR may take different forms. Driver parts or nuts 25, 45, 65, 85 and 105 respectively in FIGS. 2-4, 5, 6, 7 and 8-9 and driven parts or screws 27, 47, 67, 87, 107 and 187 in FIGS. 2-4, 5, 6, 7, 8 9 and 13 have helical surfaces 25:1, 45:1, 65:1, 85:1 :and 105:1 and 27:1, 47:1, 67:1, 87:1, 107:1 and 187:1 formed by screw threads. In FIGS. 16-17, driver part or cam actuator 245 and driven part or cam 247 are respectively rear and front barrel cams having helical surfaces 245:1 and 247:1.

Each driven part has a suitable bore 16 permitting removal of, or for telescopicaily receiving, scribe element 14 by insertion through cap end 10e when cap and barrel members and 12 are in the uncoupled position. Each bore 16 securely holds and locates scribe element 14 in the coupled positionin the different writing instruments in many dilferent manners. Each driven part 27, 47, 67, 87, 107, 167, 187, 207, 227 and 247 is sleeve-like in shape; has or is intended to have an end stop located on the end of the bore most remote from the writing end of scribe element 14 to engage scribe element end 14b for preventing writing pressure on ball point end 14:1 from causing appreciable axial movement of element 14 into barrel member 12l and bore 16 from advanced position PA; and has a collet, having a bore diameter less than the rest of bore 16 and located at the end of bore 16 closest writing end 14:1 of scribe element 14, for gripping scribe element 14 in the advanced and coupled positions. Some of the different forms of end stops illustrated include respectively in FIGS. 2, 3 and 5 portions 35:1 and 55:1 of the wall of the driven part bent inwardly over the remote end of bore 16 so that this portion is located to engage remote end 14b of scribe element 14; in FIG. 6 cap 75:1 telescoped over and secured to the remote end of driven part 67; in FIG. 8 diametrically aligned lug portions 115:1 of the wall of driven part 107 bent inwardly over the remote end of bore 16 so that these portions 115:1 engage remote end 14b of scribe element 14; and in FIGS. 12, 13 and 16 bore bottoms 175:1, 195:1 and 255:1 carried by driven parts 167, 187 and 247 respectively. The collets shown in FIGS. 2, 5, 6, 8, and 16 have portions 3511, S511, 75h, 115b and 255b with bore diameters less than the rest of each bore 16 to grip scribe element periphery 14C by either the resiliency of the material, as shown in FIG. 16, or by axially extending and equally circumferentially spaced apart splits in the last mentioned portions in the sleevelike driven part, as shown by splits 35C, 55e, 75:: and 115e, or any combination of resiliency and splits.

The rotatable connections 32, 52, 72, 92, 112, 212, 232 and 252 respectively in FIGS. 2, 5, 6, 7, 8, 14, and 16 between couplers 29, 29, 69, 89, 109, 209, 229 and 249 and associated rotatable components 31, 31, 71, 91, 111, 211, 231, and 251 may take many different forms. Connections 32, 52, 72, 112 and 252 respectively include annular grooves 32:1, 52:1, 72:1, 112:1 and 252:1 in bore surfaces 3111, 51:1, 71:1, 111:1 yand 251:1 and annular rings 3211, 52h, 72b, 112b and 252b on peripheral surfaces 29:1, 29a, 69:1, 109:1 and 249:1; and connections 92, 212 and 232 include annular grooves 92:1, 212:1 and 232:1 in peripheral surfaces 89:1 and 209:1 and annular rings 92h and 212b in bore surfaces 91:1 and 211:1 coacting together to provide relative rotative movement but to prevent relative axial movement between the coupler and its associated driver part. Grooves 32:1 and 52:1 and rings 32h and 52b have coacting surfaces forming an arc of a circle cut in each of the surfaces; and grooves 72:1 and 252:1 and rings 72b and 252b being triangular in cross section.

Prior to telescopic insertion into barrel cap bore 10d, each :associated coupler and rotatable component is assembled together. In FIGS. 2, 5, 6 and 16 respectively, rotatable components 31, 31, 71 and 251 and their bores 31a 31a, 71:1 and 251:1 have diametrically aligned axially extending splits 311, 71)c and 251f for permitting telescopic assembly of each rotatable component over' its associated coupler by having the split portions spring outwardly during travel over the associated rings. In FIGS. 7 and 14, rings 92h and 212b are contour roll formed into grooves 92:1 and 212:1 after telescopic assembly of coupler 89 and 209 and components 91 and 211. In FIG. 8, component 111 has a cylindrical counterbore formed at the left end of bore surface 111:1, ring 112b is telescoped into location in this counterbore, and `the left end of this counterbore is spun inwardly and axially down onto one side of ring 112b to form groove 112:1 over ring 112b. In FIG. 15, peripheral surface 229:1 on coupler 229 has therein annular groove 232a, bore surface 231:1 has four radially extending and equally circumferentially spaced apart holes 231/1 in axial alignment with groove 232:1, and four balls 23211, one located in each hole 231k and in radial alignment between annular groove 232:1 and cap member bore 10:1'.

Each form of writing instrument illustrated has structure providing a frictional drag action during advancing and retracting movements in directions DA and DR to take up any lost motion, to stop any free wheeling, and to stop any runaway action in the component parts. Two different type drag actions are provided, as described in the following paragraphs.

First, FIGS. 2 and 3, 6, 7, 8, 12 and'13 show respectively drag means 36, 76, 96, 116, 176 and 196 carried by driven parts 27, 67, 87, 107, 167 and 187; and having drag rings 36:1, 76:1, 96:1, 116:1, 176:1 and 196:1 engaging during movement in directions DA or DR by a frictional drag action cylindrical surfaces 37, 77, 97, 117, 177

and 197 fixed against axial relative movement relative to driver parts 25, 65, and 105 (driver parts not shown in FIGS. 12 and 13) by being either on said last-mentioned part, such as on driver part 65 in FIG. 6 and part 85 in FIG. 7, or on another component fixed relative thereto, such as on cap bore surfaces 10d in FIGS. 2, 3, 8, 12 and 13. Each such drag ring may be made of any suitable resilient material, such as felt, rubber, plastic, etc.

FIGS. 2 and 3, 6, 7, 8, l2 and 13 show different specie constructions. 1n FIGS. 2 and 3, dnag means 36 has drag ring 36:1 straddled by two Washers 33 and axially located between spun over end 27m on driven part 27 and sleeve 39 abutting against the right end of threads 27:1. In FIG. 6, drag means 76 has drag ring 76a formed integral with driven part 67. In FIGS. 7 and 8, drag means 96 has drag ring 96:1, and drag means 116 includes drag ring 116:1 telescopically connected respectively over driven parts 87 and 107 with each drag ring having an annular groove, generally triangular in cross section, in one axial face thereof. In FIG. 7, drag ring 96:1 and driven part 87 have respectively frictionally contacting bore and peripheral surfaces, and drag ring 96:1 is held against axial movement in `one direction by C-snap ring 98 located in a groove in the periphery of driven part 87. In FIG. 8, drag means 116 includes annular carrier 118 telescopically located between drag ring 116:1 and driven part 107 and being swedged at assembly, as shown in FIG 9, to lock it against rotation and axial movement on threads 107:1. FIG 12 has drag means 176 including drag ring 176:1 straddled by washers 178 and connected to the end of driven part 167 by rivet 179 telescoped through aligned holes in drag ring 176:1, Washers 178 and driven part 167. In FIG. 13, drag means 196 includes drag ring 196:1 telescoped over sleeve 199:1 on sleeve-like carrier 199 and secured thereon by washer 198 and sleeve end 199b spun over at assembly. `Opposite end 199C 0f carrier 199 is telescopically connected over the right end of driven member 187 and has ears 199:1 pushed inwardly during assembly into aligned holes in driven member 187.

Second, drive mechanism 44 in FIG. 5 and 244 in FIG. 16 includes drag means 56 and 256 comprising respectively helical compression springs S7 and 257 axially pushing parts 45, 47 and 245, 247 and their helical surfaces 4511, 47:1 and 245:1, 247:1 axially together to provide a frictional drag action during advancing or retracting movement in direction DA or DR. These helical surfaces are screw threads 45a, 47a in FIG. 5 and cam surfaces 245a, 247a on coacting barrel cams in FIG. 16. In FIG. 5, the right hand end of spring 57 bears against washers 58a, 58h axially located between spun over end 47m on driven part 47 and sleeve 59 abutting against the right hand end of threads 47a. Washers 58a and 58b are preferably made of different materials to avoid any jumpy drive action caused Iby differences in friction caused when washers made of the same material try to rotate relative to each other. If washer 58h is made of steel, washer 58a is preferably made of neoprene, rubber, oil soaked felt, ber, cardboard, etc. to give a smooth drive action.

An examination of the drawings will reveal in FIGS. 2-4, 5, 6, 7, 8-9, and 16 respectively that advanced positions PA are defined by engagement of end stops 33a and 33b respectively on driver part 25 and on sleeve 39 carried by driven part 27; 53a and 53b respectively on driver part 45 and on sleeve 59 carried by driven part 47; 73a and 7317 respectively on coupler 69 and drag ring 76a carried by driven part 67; 93a and 93b respectively on coupler 89 and drag ring 96a on driven part 87; 113a and 113b respectively on driver part 105 and carrier 118 on driven part 107; and 253a and 253b respectively on driver part 245 and driven part 247 and that retracted positions PR are defined by .engagement of end stops 34a and 34b respectively on driver part 25 and driven part 27; 54a and 54b respectively on driver part 45 and driven part 47; 74a and 74b respectively on driver part 65 and drag ring 76a carried by driven part 67; 94a and 94b respectively on driver part 85 and snap ring 98 on driven part 87; 11411 and 114b respectively on driver part 105 and driven part 107; and 254g and 254b respectively on driver part 245 and driven part 247. The drag means 176 and 196 in FIGS. 12 and 13 are adapted to be substituted for the drag means 36 and 116 in FIGS. 3 and 8 so have the same end stops except end stop 193b in FIG. 13 is then used in place of end stop 113b in FIG. 8.

Pens and 160 in FIGS. 2, 3 and 12 are constructed so that the parts are automatically locked in advanced position PA. Consider FIG. 3 as an example. Sleeve 39, drag ring 36a and washers 38 are telescopically connected over and axially movable relative to driven part 27. Drag ring 36a and washers 38 are axially located between spun over end or stop 27m and the right end of sleeve 39. As driven part 27 moves in advancing direction DA into writing or advanced position PA, the left end of sleeve 39 engages as end stop 33b against driver part as end stop 33a to push sleeve 39 over driven part 27 toward stop 27m for radially squeezing or deforming Y resilient drag ring 36a outwardly into a frictionally locked, advanced position pushed outwardly against cylindrical surface 37.

Although different methods of assembly may be used for each pen illustrated here in the drawings, a brief description of one suitable assembly method for pen 420 in FIGS. 2. and 3 will illustrate the principles involved. Ferrule 23, tip 10b and tip 12b are telescopically press fitted into the appropriate cap 10 or barrel 12. Driver member 25 is axially telescoped toward the left over rotatable component 29, axial splits 31)c are forced open by ring 32, and groove 32a and ring 32b snap assembled to form a unit then telescoped in the left hand direction over driven part v27. After assembly is completed by telescoping together hexagonal surfaces 27b and 29h and by screwing threads 25a and 27a together, sleeve 39, washers 38 and drag ring 36a are telescoped over the right end of driven member 27 and end 27m is spun over to complete this unit. Then, this unit is telescoped axially toward the right through cap end 10e into cap bore 10d within which the left end of the periphery of component 29 iits with a press t to at least partially close up splits t 311 and cause them to grip bore 10d tightly.

It should be readily apparent that each of the aforedescribed members, parts, elements, components, couplers, etc. other than the drag rings and helical springs may be made from any suitable material, such as plated or unplated brass; aluminum; molded plastic, such as such as nylon; etc.

Since each form of writing instrument disclosed herein operates in generally the same manner, the method of operation of only pen 20 in FIGS. 1-4 will |be described here. A replacement can be made for scribe element 14 ing scribe element 14 'between retracted and advanced position PR and PA, and for moving cap 10 and barrel 12 to uncoupled position. During all of these movements all screw threads 22a, 23a, 25a and 27a have some relative movement. For purposes of illustration, let us say` that threads 22a and 23a are 1%: inch-56 pitch, single lead right hand threads and that threads 25a and 27a are #l0-24 pitch, double lead, left hand threads, which are the specific threads used in a working model of pen 20.

These sequential movements are relative rotation of cap 10 and barrel 12: (1) in a first direction to move members 10 and 12 from uncoupled to lcoupled positions, (2) in either opposite directions in this coupled position by only a scribe element actuating force to move scribe element 14 between advanced position lPA and retracted position PR defining scribe element end positions without uncoupling members 10 and 12, or (3) in the opposite of the said first direction in one of the scribe element end positions, PR or PA, by an uncoupling force greater than the scribe element actuating force to move members 10 and 12 to the uncoupled position. In the specific thread example given with the threads being of opposite hand, the movements in the aforesaid first and in the rst of the opposite directions are sequential movements in the same direction first coupling members 10 and 12 and then moving scribe element 14 to advanced position PA. To understand the sequence of these movements more clearly, assume that the components of pen 20 start in the solid line position shown in FIG. 2. Then, relative rotation of cap 10 and barrel 12: (l) in the first direction will cause cap 10 to directly screw threads 22a onto threads 23a by a rigid drive from cap 10 through component 31, driver part 25,

threads 25a and 27a rigidly locked against axial movement by engaged retracted position end stops 34a and 34b, and hexagonal surfaces 27b and 2911 to coupling threads 22a; (2) in the same direction so that further rotation of barrel 10 in the same direction sequentially unlocks end stops 34a and 34b and rotates drive part 25 on driven part 27 to advance part 27 and scribe element 14 in ad-' vancing direction DA from retracted position PR shown in solid lines in FIG. 2 to advanced position PA shown in dot-dash lines where end stops 33a and 33b engage and lock up while the hexagonal surfaces 27b and 29b prevent rotation of driven part 27 with driver part 25;`

(3) in the opposite direction sequentially to unlock in position PA end stops 33a and 33b and to move driven part 27 and scribe element 14 in retracting direction DR' from advanced position PA to retracted position PR through drive mechanism 24 in the same manner until end stops 34a and 34b again lock up, as shown in solid lines in FIGS. 2; or (4) in the opposite of said first direction with end stops 33a and 33b locked up in retracted position PR by an uncoupling force exerted from barrell 10 through component 31, driver part 25, threads 25a Now, the movements will be sequentiallyy 9 and 27a rigidly locked against axial movement by engaged retracted position end stops 34a and 34h, and hexagonal surfaces 27b and 29b to coupling threads 22a.

To have this mode of operation, threads 22a, 23a in coupling means 21 and threads 25a and 27a must have a definite relationship. Since this same relationship can exist for any form of the pens shown in FIGS. 1-17, let us consider the relationship broadly for all. Note we have to consider: (1) three different type coupling means 21 in FIG. 2, 121 in FIG. 10, and 141 in FIG. 11; and (2) two different type helical surfaces, including threads 25a and 27a in FIGS. 2 and 3 and cam surfaces 245a and 247a in FIGS. 16 and 17.

To establish the necessary relationship, the helical surfaces and coupling means in any one of these Writing instruments must be constructed so that, Aduring relative rotation of members 10 and 12 in the coupled position, any of the following factors are true: (l) the rotatable gripping force by lock up at any such coupling means is greater than the rotatable gripping force by lock up at the coarse actuating threads 25a, 27a; (2) the helical surfaces 25a, 27a and 245g, 247a are always unlockable by relative rotation of members 10 and 12 without uncoupling any such coupling means; (3) ooarser threads 25a, 27a must be able to unlock without unlocking finer threads 22a, 23a; (4) any such coupling means is frictionally snug enough in the direction of relative rotation of members 10 and 12 in the coupled position for permitting at all times relative sliding movement between helical surfaces 25a, 27a and 24511, 247a in either advancing or retracting directions DA or DR but free enough to be uncoupled. by an uncoupling force whenever desired; or (5) the lead on the helical surfaces 25a, 27a and 245a, 247a is greater than the lead on any helical surfaces of any coupling (such as on threads 22a and 23a on coupling means 21) so that not only scribe element 14 can be advanced and retracted rapidly -but also coupling means 21 has the aforesaid frictionally snug Ibut free enough characteristics.

If not only the drive means but also the coupling means has helical surfaces, this relationship may be mathematically expressed Iby -use of the scientifically established wedge formula describing the lock up action at all helical surfaces, such as for example between threads 22a, 23a and threads 25a; 27a. Although four possible conditions can exist by different combinations of right and left hand threads of the same or different hands, they are all graphically illustrated in FIG. 18 by (reading from left to right) threads 22a, 23a having thread helix angle 2A1; threads 25a, 27a having helix angle 2A2 and having a hand opposite threads 22a, 23a; and threads 25a, 27a having helix angle 2A2 and having the same hand as threads 22a, 23a. In each of the live V-vertices in FIG. 18, there is an unprimed P force driving the thread wedge together and a primed P force pulling the thread wedge apart at each locked position. Since threads 25a, 27a jam or lock up against straddling right angle shoulders defining positions PA and PR, each diagram for threads 25a, 27a has one lock up position above and the other lock up position below the horizontal line and designated either advanced position PA or retracted position PR.

Before examining the wedge formula let us first consider the action with threads of opposite hand and second with the threads of the same hand in FIGS. 2 and 3. First, if threads 22a, 23a are right hand and threads 25a, 27a are left hand threads so as to be of opposite hands. the sequence of movements and wedge actuating forcee are as follows if we start with members and 12 in uncoupled position and scribe element 14 in retracted position PR: (l) members 10 and 12 are moved into and locked in coupled position lby force P1 exerted in one `direction (downward in FIG. 18); (2) further movement in this same one direction uncouples end stops 34a, 34b in position PR by force P3 until force P2 locks up end stops 33a, 33b in position PA; (3) movement in the opposite direction (upward in FIG. 18) unlocks by force P2 end stops 33a, 33h in position PA; (4) further movement in this opposite direction locks up end stops 34a, 34h b-y force P3 in retracted position PR; and (5) further movement in this opposite direction uncouples threads 22a, 23a by force P1. Second, if threads 22a, 23a and 25a, 27a are of the same hand, the sequence of movements and wedge actuating forces are as follows if we start with members 10 and 12 in uncoupled position and scribe element 14 in advancedpostz'on PA: (l) members 10 and 12 are moved into coupled position by force P1 exerted in the same one direction (downward in FIG. 18); (2) further movement in this same one direction uncouples end stops 33a, 33b in position PA by force P5' until force P4 locks up end stops 34a, 34b in position PR; (3) movement in the opposite direction (upward in FIG. 1S) unlocks by force P4 end stops 34a, 34h in position PR; (4) further movement in this opposite direction locks up end stops 33a, 33h by force P5 in advanced position PA; and (5) further movement in this opposite direction uncouples threads 22a, 23a by force P1.

Now, it should be noted that the five different necessary relationships set forth in the third preceding paragraph must exist between wedge opening forces P1' and P2 in position PA for threads of opposite hand and between wedge opening forces P1 and P4 in position PR for threads of the same hand.

Now, let us consider the scientific wedge formula. This formula sets forth the wedge forces acting on each screw thread at lock up as follows:

P=2Q(f cos A-l-sin A) if the reference numeral suffixes in each of the iive V- diagrams in FIG. 18 are ignored. Prime suflixes designate the reversed or negative forces in the formula for unlocking each wedge at uncoupling position or position PA `or PR, and prefix X has been added to designate the cosine component of force P exerted by relative rotation of cap 10 and barrel 12. Then, the aforedescribed relationship requires for threads of the same hand:

xP4 xPl' and for threads of different hands:

xP2' xPl' so that the rotatable unlocking force at threads 25a, 27a

is less than the rotatable unlocking force at threads 22a, 23a. When the wedge formula is substituted in the last two equations with the cosine components of the P forces, these relationships become the following general formula:

wherein A, f, and Q apply to the characteristic of any thread 25a, 27a having in FIG. 18 suffix 2, 3, 4 or 5 and being either primed or unprimed. It should be noted that suffix l refers to wedge-type coupling surfaces 22a, 23a; the remaining factors refer to helical surfaces 25a, 27a; f is the coetlicient of friction of the selected threads; 2A is the helix angle of the selected threads; Q are the forces acting on the sides of the selected thread wedge; and P is the force driving the selected thread wedge into locked position. It is believed that as long as this relationship exists, the locking and unlocking action Will occur properly.

Note that the coeiicient of friction f on each pair of threads depends upon the metallic or non-metallic materials composing, and any plating thereon, the coacting threaded parts.

Although this formula has been derived and the aforedescribed iive necessary relationships have been explained only for threads 22a, 23a, 25a and 27a, it should be apparent that this same formula applies when threads 25a, 27a are replaced by cam surfaces 245g, 24701; or threads 22a, 23a are replaced by bayonet surface 12211, 123:1 in

1 1 FIG. l0, if such surfaces lock by a wedging action. Of the aforedescribed tive necessary relationships, Nos. (l) and (4) apply for any coupling means 121 or 141 in FIG. or 11 used, with or without a wedging action. Then the afore-mentioned formula becomes:

Q()c cos A-l-sin A) cos A F wherein F is the rotatable uncoupling force and the other factors are the same as before. v

It is preferred that threads 22a,` 23a be right hand threads; threads a, 27a be left hand; and the threads thus be of opposite hand for the following numbered reasons. First, the directions of rotation of cap 10 relative to barrel 12 to move scribe element 14 in advancing direction DA and in retracting direction DR are the same as in the conventional lead pencil. Second, the movements of coupling threads 22a, 23a and of advancing scribe element 14 in direction DA from retracted position PR to writing position PA are sequential rotations in the same directions, and the movements of retracting scribe element 14 in direction DRfrom w-riting position PA to retracted position PR and of uncoupling threads 22a, 23a are sequential movements in the opposite direction. Hence, minimum change of direction of movement, and smoothest and most natural operation, always puts scribe element 14 in the proper writing position PA, retracted position PR, uncoupled position for replacing element 14, or coupled position for pen useage. Third, the scribe element bore and the end of the driven part (such as bore 16 and the left end of driven part 27 in FIG. 2) will always be located in retracted position PR, when members 10 and 12 are in uncoupled position, so as to project the minimum distance from the outer end of coupling element 22 and cap 10 so as to provide then the mostattractive appearance. Compare these features with those found in the aforedescribed operation of threads of the same hand; in a pen Where threads 22a, 23a are left hand threads and threads 25a, 27a are right hand threads; or in the prior art.

Here are some of the advantages of the different forms of writing instruments disclosed herein and illustrated in drawing FIGS. 1-17. First, any standard type ball point pen rell cartridge or element 14 can be used. Second, each writing instrument is of simple construction and has few component parts. Third, the user loads scribe element 14 through the middle of each writing instrument between contiguous ends 10e and 12e, instead of through one end of the writing instrument. Fourth, each writing instrument is attractive and distinctive in appearance. Fifth, each writing instrument uses a relative rotating movement of cap 10 and barrel 12 to advance and retract scribe element 14 and/ or to couple or uncouple cap 10 and barrel 12 during replacing or changing of scribe elements 14 therein. Sixth, for a given arcuate relative rotation -of cap 10 and barrel 12, each writing instrument has greater axial movement by said advancing and retracting movements movable in directions DA and DR than by the coupling and uncoupling action, whereby scribe element 14 is quickly moved to any position PA or PR desired. This is true because, for example in FIG. l, the lead of threads 25a, 27a is greater than threads 22a, 23a. Seventh, relatively rotating cap 10 and barrel 12 causes movement of scribe element 14 in direction DA or DR and/ or causes coupling or uncoupling of cap 10 and barrel 12 by a positive drive (including press ts between cap 10, barrel 12 and their associated drive mechanism) instead of relying on frictional drive, friction slippage or a slip t drive. Eighth, each writing instrument has a drive mechanism adapted to be readily used with any type scribe element 14, whether ball point pen or mechanical pencil lead. lNinth, each writing instrument has all of the relatively movable components in its drive mechanism assembled together into an assembly pressed into cap 10 so as: (1) to be locked therein with no possibility of disassembly in any position, (2) to be approximately ush with cap end 10e and barrel end 12e,

12 exceptfor projecting threads 10a, in uncoupled position to provide an attractive appearance, and (3) to permit relative opposite directions of rot-ations of cap `10 and barrel 12 not only to move scribe element 14 in advanc-` ing and -retracting direction DA and DR but also -to move cap 10 and barrel 12 between coupled and uncoupled positions.

This invention may be embodied in other specific formswithout departing from the spirit or essential characteris-` tics thereof. The present embodiments are therefore to be considered in all -respects as illustrative and not restrictive with the scope of the invention being indicated by the appended claims rather than by the foregoing de-` scription, and all changes which come Within the meaning and range of equivalency of the claims are therefore:l

(e) said drive mechanism including a bore for driv-` ingly receiving a scribe element through the un-` coupled end of said one member,

(f) said drive mechanism including a driver part responsive to relative rotational movement of said one member in said coupled position relative to the other of said members for moving said scribe element be-y tween an advanced and a retracted position,

(g) said drive mechanism including with said driver part a driven part having cooperating coacting helical surfaces rotated by said barrel and cap members for causing'said advancing or retracting movement of said driven part,

(h) said driver part being rigidly carried by said one;

member by a press t, (i) a coupler operatively carried by said other member in said coupled position,

(j) said driven parts being axially slidable in-said coupler,

(k) whereby advancing and retracting movement of said scribe element by relative rotational movement of said members is a positive drive not relying on frictional slippage.

2. An assembly comprising a drive unit for a writing instrument including a cap member and a barrel member and a coupling means movable 'between uncoupled and coupled positions for detachable connecting by a coupling movement the contiguous ends of said members, compris- (a) drive mechanism operatively connected to one of said members,

(b) said drive mechanism including a bore for driving-k` ly receiving a scribe element through the uncoupled end of said one member, (c) said drive mechanism including a driver part responsive to relative rotational movement of said one` member in said c-oupled position relative to the other of said members for moving said scribe element between an advanced position and a retracted position` with the other of said members in said coupled position closing said uncoupled end on said one member,

(d) said drive mechanism including with said driver part a driven part having cooperating coacting helical surfaces rotated by said 'barrel and cap members for causing said advancing or retracting movement of said driven part,

(e) a coupling means as described,

(f) said helical surfaces and said coupling means being constructed so that said helical lsurfaces are operably unlock-able during relative rotational movement of said barrel and cap members without uncoupling said coupling means.

3. An assembly comprising a drive unit for a writing instrument including a cap member and a barrel member and a coupling means movable between uncoupled and coupled positions for detachable connecting by a coupling movement the contiguous ends of said members, comprismg (a) drive mechanism operatively connected to one of sai-d members,

(b) said drive mechanism including a bore for drivingly receiving a scribe element through the uncoupled end of said one member,

(c) said drive mechanism including a driver part responsive to relative rotational movement of said one member in said coupled position relative to the other of said members for moving said scribe element between an advanced position and a retracted position,

(d) said drive mechanism including with said driver part a dnven part having cooperating coacting helical surfaces rotated by said barrel and cap members for causing said advancing or retracting movement of said `driven part,

(e) a coupling means as described,

(f) said parts having end stops respectively engageable in said advanced and retracted positions to define locked positions by the wedging action between said parts caused by said helical surfaces,

(g) said helical surfaces and said coupling means 'being constructed so that said helical surfaces are operatively unlockable from said locked positions during relative rotational movement of said barrel and cap members without uncoupling said coupling means.

4. An assembly, as set forth in claim 3, with (a) said coupling means having rotatable Wedge-type coupling surfaces coupling said members together in said coupled position,

(b) the unlocking force bearing the following ratio to the rotatable uncoupling force:

Q(f cos A-l-sinA) cos A Ql(fl cos Al-l-sinAl) cos/11 wherein fl is the coefficient of friction of the wedgetype coupling surfaces, A1 is 1/2 the helix angle of the wedge-type coupling surfaces, Q1 are the forces acting on the sides of wedge-type coupling surfaces, f is the coefficient of friction of the helical surfaces, A is 1/2 the helix angle of the helical surfaces, and Q are the forces acting on the sides of the selected helical surfaces.

5. An assembly, as set forth in claim 3, with (a) the unlocking force bearing the following ratio to said rotatable uncoupling force:

QU cos A-l-sin A) cos A F wherein F is the rotatable uncoupling force, f is the coeicient of friction of the helical surfaces, A is 1/2 the helix angle of the helical surfaces, and Q are the forces acting on the sides of the helical surfaces.

6. An assembly comprising a drive unit for a writing instrument including a cap member and a barrel member and a coupling means movable between uncoupled and coupled positions for detachable connecting by a coupling movement the cont-iguous ends of said members, cornprising (a) drive mechanism operatively connected to one of said members,

(b) said drive mechanism including a bore for drivingly receiving a scribe element through the uncoupled end of said one member,

(c) said drive mechanism including a driver part responsive to relative rotational movement of said one member in said coupled position relative to the other of said members for moving said scribe element between an advanced position and a `retracted position i4 with the other of said members in said couple-d positi-on closing said uncoupled end on said one member, (d) said drive mechanism including with said driver part a driven part having cooperating coacting helical surfaces rotated by said barrel and cap members for causing said advancing or retracting movement of said -driven part, (e) a coupling means as described, (f) coupling lock up at the coupling means providing a rotatable gripping force, (g) said rotatable lgripping force being greater than the rotatable gripping rforce by lock up at said helical surfaces. 7. A writing instrument, comprising (a) a cap member, (b) a bar-rel member connected t0 said cap member, (c) coupling means for detachably connecting said members with the members movable between uncoupled and coupled positions, and (d) drive mechanism operatively secured in at least one of said members, (e) said drive mechanism including a bore for drivingly receiving a scribe element through the uncoupled end of said one member, (f) said drive mechanism including a driver pa-rt responsive to relative rotational movement of said one member in said coupled position relative to the other of said members for moving said scribe element between an advanced and a retracted position, (g) said drive mechanism including with said driver part a driven part having cooperating coacting helical surfaces rotated by said barrel and cap members for causing said advancing or retracting movement of said driven part, (h) said drive mechanism and coupling means being operable by relative rotational movement of said members so that relative rotational movement of said members:

(l) in a rst direction, will move said members from said uncoupled to said coupled position, (2) in the opposite of said rst direction, will move said members from said coupled to said uncoupled position, and

(3) when in coupled position, movement in either direction will move said scribe element between scribe element advanced and retracted positions without uncoupling said members,

(i) the other of said members in said coupled position closing said uncoupled end on said one member.

8. A writing instrument, as set forth in claim 7, with (a) said drive mechanism being constructed so that the surface of said bore for said scribe element in uncoupled position projects the minimum distance out of said one member.

9. A writing instrument, las set forth in claim 8, with (a) said parts and said coupling means having threads of opposite hands.

10. An assembly comprising a drive unit for a writing instrument including a cap member and a bar-rel member and a coupling means movable between uncoupled and coupled positions for detachable connecting by a coupling movement the contiguous ends of said members, comprislng (a) drive mechanism operatively connected to one of said members,

(b) said drive mechanism including a bore for drivingly receiving a scribe element through the uncoupled end of said one member,

(c) said drive mechanism including a driver part responsive to relative rotational movement of said one member in said coupled position relative to the other of said members for moving said scribe element between an advanced position and a retracted position With the other of said members in said coupled position closing said uncoupled end on said one member,

(d) said drive mechanism including with said driver part a driven part having cooperating coacting helical surfaces rotated by said barrel and cap members for causing said advancing or retracting movement of said driven part,

(e) a coupling means as described,

(f) said coupling means being frictionally snug enough during any attempted movement in the direction of relative rotation of said members in said coupled position forpermitting at all times relative operative sliding movement between said helical surfaces in either advancing or retracting directions but with said coupling means being free enough to be uncoupled when desired.

11. An assembly, as set forth in claim 10, with (a) said coupling means including two cylindrical telescopically and rotatably connectable surfaces having a snug fit and carried one by each member.

12. An assembly, as set forth in claim 10, with (a) said parts including barrel cams having said helical surfaces.

13. An assembly, as set forth in claim 10, with (a) said parts having said helical surfaces formed by screw threads.

14. An assembly, as set forth in claim 10, with (a) said coupling means having a helical surface providing said coupling action,

(b) the lead on the helical surfaces on said drive mechanism parts 'being greater than the lead on the helical surface on said coupling means, whereby said scribe element can be advanced and retracted rapidly and said coupling means has the aforedescri-bed frictionally snug but free enough characteristics.

15. An assembly comprising a drive unit for a writing instrument including a cap member and a barrel member and a coupling means movable between uncoupled and coupled positions for detachable connecting by a coupling movement the contiguous ends of said members, comprising (a) dri-ve mechanism operatively connected to one of said members,

(b) said drive mechanism including a bore for drivingly receiving a scribe element through the uncoupled end of said one member,

(c) said drive mechanism including a driver part responsive to relative rotational movement of said one member in said coupled position relative to the other of said members for moving said scribe element between an advanced position and a retracted position,

(d) said drive mechanism including with said driver part a driven part having cooperating coacting helical surfaces rotated by said'barrel and cap members for causing said advancing or retracting movement of said driven part,

(e) a coupling means as described,

(f) said coupling means being frictionally snug enough during any attempted movement in the direction of relative rotation of said members in said coupled position for permitting at all times relative operative sliding movement between said helical surfaces in either advancing or retracting directions 'but with said coupling means being free enough to be uncoupled when desired,

(g) said coupling means including two rotatably and connectable bayonet surfaces carried one by each member.

16. A writing instrument, comprising (a) a cap member,

(b) a barrel member connected to said cap member,

`(c) coupling means for detachably connecting said members with the members Imovable between uncoupled and Acoupled positions, and

(d) drive mechanism operatively secured in at least one of said members,

(e) said drive mechanism including a bore for drivingly receiving a scribe element through the uncoupled end of said one member,

(f) said drive mechanism including a driver part responsive to relative rotational movement of said one member in said coupled position relative to the other of said members for moving said scribe element 'between an advanced and a retracted position,

(g) said drive mechanism including with said driver part a driven part having cooperating coacting helical surfaces rotated by said barrel and cap members for causing said advancing or retracting movement of said driven part,

I(h) said driver part being operatively secured to said one member against relative axial and rotative.`

movement, d d (i) said drive mechanism including a coupler operatively secured to the other of said members lby said coupling means against relative axial and rotative` movement in said coupled position,

(j) said coupler and said driven part being connected by a keyed connection permitting axial relative movement in said advancing and retracting directions.

17. A writing instrument, as set forth in claim 16,=

said connection, one of said surfaces being `arpe-` ripheral surface and the other of said surfaces being a bore surface.

18. A writing instrument, as set forth in claim 17,`

with

(a) one of said surfaces having an annular groove therein,

(b) the other of said surfaces having an annular ring thereon,

(c) said ring and groove coacting together for preventing relative axial movement between said coupler and said driver part.

19. A writing instrument, as set forth in claim 18,

with

(a) said groove and ring each being triangular in cross section.

20. A writing instrument, as set forth in claim 18,I

with

(a) one of said surfaces having at least one axially extending split for permitting telescopic assembly of said coupler and said component.

21. A writing instrument, as set forth in claim 17, with (a) one of said surfaces having an annular groove therein,

(b) the other of said surfaces having at least one hole extending radially therethrough in axial alignment i with said groove,

(c) said one member having a bore,

(d) and a ball located in said hole between said an.

nular groove and the bore in said one member.

22. A drive unit for a writing instrument including a cap member and a barrel member and a coupling mean's f moveable between uncoupled and coupled positions for detachable connecting by a coupling movement thel contiguous ends of said members, comprising (a) drive mechanism operatively connected to `one of said members, (b) said drive mechanism including a bore for driv ingly receiving a scribe element through the uncoupled end of said one member,

(c) said drive mechanism including a driver part 'responsive to relative rotational movement of said one member in said coupled position relative to the other of said members for moving said scribe element between an advanced position and a retracted position,

(d) said drive mechanism including with said driver part a driven part having cooperating coacting helical surfaces rotated by said barrel and cap members for causing said advancing or retracting movement of said driven part,

(e) a cylindrical surface,

(f) one of said parts being fixed against axial movement relative to said cylindrical surface,

(g) said drive mechanism including a drag means carried by the other of said parts telescopically engaging -and rotatable lrelative to said cylindrical surface -by a frictional drag action during said advancing or retracting movement.

23. A drive unit for a writing instrument including a cap member and a barrel member and a coupling means movable between uncoupled and coupled positions for detachable connecting by a coupling movement the contiguous ends of said members, comprising (a) drive mechanism operatively connected to one of said members,

(b) said drive mechanism including a -bore for drivingly receiving a scribe element through the uncoupled end of said one member,

(c) said drive mechanism including a driver part responsive to relative rotational movement of said one member in said coupled position relative to the other of said members for moving said scribe element between an advanced position and a retracted position,

(d) said drive mechanism including with said driver part a driven part having cooperating coacting helical surfaces rotated by said barrel and cap members for causing said advancing or retracting movement of said driven part,

(e) a cylindrical surface,

(f) one of said parts being fixed -against axial movement relative to said cylindrical surface,

(g) said drive mechanism including a drag means carried by the other of said parts telescopically engaging said cylindrical surface by a frictional drag action during said advancing or retracting movement,

(h) 4said drag means including a drag ring integral with said other part.

24. A drive unit for a writing instrument including a cap member and a lbarrel member and a coupling means movable between uncoupled and coupled positions for detachable connecting by a coupling movement the contiguous ends of said members, comprising (a) drive mechanism operatively connected to one of said members, Y

(b) said drive mechanism including a bore for drivingly receiving a scribe element through the uncoupled end of said one member,

(c) said drive mechanism including a driver part responsive to relative rotational movement of said one member in said coupled position relative to the other of said members for moving said scribe element between an advanced position and a retracted position,

(d) said drive mechanism including with said driver part a driven part having cooperating coacting helical surfaces rotated by said barrel and cap members for causing said advancing or retracting movement of said driven part,

(e) a cylindrical surface,

18 (f) one of said parts being xed against axial movement relative to said cylindrical surface,

(g) said drive mechanism including a drag means carried `by the other of said parts telescopically engaging said cylindrical surface by a frictional drag action during said advancing or retracting movement,

' (h) said drag means including a drag ring telescopically connected to said other part 'and engaging said cylindrical surface by a frictional drag action during said advancing or retracting movement.

25. A drive unit for a writing instrument, as set forth in claim 24, with in claim 24, with (a) said drag ring being connected to said other part by a sleeve-like carrier telescopically connected at opposite ends to said other part and to said drag ring.

28. A drive unit for a Writing instrument, as set forth in claim 24, with (a) la sleeve telescopically connected to said other part,

(b) an axial stop carried by said other part,

(c) said sleeve and drag ring being axially movable relative to said other part,

(d) said drag ring being :axially located between one end of said sleeve and said stop,

(e) the other end -of said sleeve engageable with said one part in said advanced position,

(f) said drag ring being made of radially deformable material,

(g) whereby relative advancing movement of said parts to said writing or advanced position causes said sleeve to be pushed tby said one part toward said stop for radially deforming said dragring into a frictionally locked position against said cylindrical surface.

29. A drive unit for :a Writing instrument including a cap member and a barrel member and a coupling means movable between uncoupled and coupled positions for detachable connecting by a coupling movement the contiguous ends of said members, comprising (a) drive mechanism operatively connected to one of said members,

(b) said drive mechanism including a ybore for drivringly lreceiving a scribe element through the uncoupled end of said one member,

(c) said drive mechanism including a driver part responsive to relative rotational movement of said one member in said coupled position relative to the other of said members for moving said scribe element between an advanced position and a retracted position,

(d) said drive mechanism including with said driver part a driven part having cooperating coacting helical surfaces rotated by said `barrel and cap members for causing said advancing or retract-ing movement of said driven part,

(e) said drive mechanism including a drag means cornpnising a helical compression spring axially pushing said helical surfaces on said parts axially together to provide a frictional drag action during said advancing or retracting movement.

30. A drive unit for a Iwriting instrument, as set forth in clairn 29, with (a) said helical surfaces being screw threads.

1 9 20 31. A drive unit for a writing instrument, as set forth 2,753,844 7/ 1956 Boss 120-18 X Iin claim 29, with 3,106,908 10/1963 Gretz 120-18 (a said helical surfaces being cam surfaces on coact- FOREIGN PATENTS lng barrel cams.

5 8,198 2/1904 Great Britain. References Cited by the Examiner Of 1903 424,069 2/ 1935 Great Britain. UNITED STATES PATENTS 693,561 7/1953 Great Britain. 954,415 4/ 1910 Homan 120-4202 785,249 10/1957 Great Britain. 2,291,859 8/1942 Andrews 120-42.04 X 2,304,229 12/1942 AndfeWS 120-42-04 X 10 EUGENE R. CAPOZIO, Primary Examiner. 2,454,086 11/1948 Randolph 12042.03 l 2,565,556 s/1951 Gruber 12o-42.03 JEROME SCHNALL Ewmme" 2,565,601 8/ 1951 Fischer 1Z0-42.03 E. HOROWITZ, H. F. ROSS, Assistant Examiners. 

1. A WRITING INSTRUMENT, COMPRISING (A) A CAP MEMBER, (B) A BARREL MEMBER CONNECTED TO SAID CAP MEMBER, (C) COUPLING MEANS FOR DETACHABLY CONNECTING SAID MEMBERS WITH THE MEMBERS MOVABLE BETWEEN UNCOUPLED AND COUPLED POSITIONS, AND (D) DRIVE MECHANISM OPERATIVELY SECURED IN AT LEAST ONE OF SAID MEMBERS, (E) SAID DRIVE MECHANISM INCLUDING A BORE FOR DRIVINGLY RECEIVING A SCRIBE ELEMENT THROUGH THE UNCOUPLED END OF SAID ONE MEMBER, (F) SAID DRIVE MECHANISM INCLUDING A DRIVER PART RESPONSIVE TO RELATIVE ROTATIONAL MOVEMENT OF SAID ONE MEMBER IN SAID COUPLED POSITION RELATIVE TO THE OTHER OF SAID MEMBERS FOR MOVING SAID SCRIBE ELEMENT BETWEEN AN ADVANCED AND RETRACTED POSITION, (G) SAID DRIVE MECHANISM INCLUDING WITH SAID DRIVER PART OF DRIVEN PART HAVING COOPERATING COACTING HELICAL SURFACES ROTATED BY SAID BARREL AND CAP MEMBERS FOR CAUSING SAID ADVANCING OR RETRACTING MOVEMENT OF SAID DRIVEN PART, 